THE COMMENT: “In the CREDO report and in, I believe, the Brookings Institute report, both within a couple of years … charter school students in Arizona on average are academically behind their district counterparts.”

THE FORUM: An interview with The Arizona Republic.

WHAT WE'RE LOOKING AT: Whether charter schools students in Arizona are behind their public school counterparts in academic performance.

ANALYSIS: Morrill cites two reports chronicling the performance of charter schools in Arizona and elsewhere.

The Center for Research on Education Outcomes at Stanford University report he references was released in 2013 and compared students' academic growth in math and reading.

The study states that, on average, Arizona charter school students are behind their public school counterparts by the equivalent of 22 days of learning in math and 29 days of learning in reading. In a separate study released in 2015, CREDO found similar averages for charter schools in Phoenix and Mesa. In Tucson, however, it didn’t find a significant difference in reading growth, but charter schools students did better than their public school counterparts in math.

The other report Morrill references was released by the Brookings Institution in 2014 and states Arizona charter schools “do no better, and sometimes worse, than the traditional public schools.”

This report makes a slightly different point than Morrill, who said that charter schools students were behind. The report notes that relying on averages to compare performance misses the significant differences among individual charter schools. Nationally, charter schools show more variability in performance than public schools, the report states.

Eileen Sigmund, president of the Arizona Charter Schools Association, said the data in the CREDO report is outdated and doesn't reflect improvements in recent years. According to a fact sheet from the association, 135 charter schools improved one letter grade in the Arizona Department of Education’s 2014 report on school performance, possibly indicating charter schools, on the whole, are improving.

BOTTOM LINE: Part of Merrill's statement is correct: A 2013 CREDO study did find Arizona charter schools were behind public schools on average. The other study he references from the Brookings Institution shows charter schools “do no better, and sometimes worse" than public schools, which doesn't directly support what he is saying. The Brookings report also says there was more variation in charter school performance nationally, making it unclear how meaningful it is to compare such performance averages. Furthermore, there is data to suggest charter schools have improved student performance since the release of those reports.